Robot device

ABSTRACT

A walking-on-four-legs type robot whose body is connected at the front right, front left, rear right, and rear left with legs is adapted so that its action saves the user trouble and increases the user&#39;s affection for, and curiosity about, the robot.

TECHNICAL FIELD

The present invention relates to a robot, and is preferably applied to,for example, a walking-on-four-legs type pet robot.

BACKGROUND ART

The inventor recently developed a walking-on-four-legs type pet robot.The pet robot spontaneously acts in response to an ambient environment,the user's action, etc.

Making such a robot be able to recover from a tumble by itself saves theuser the work of standing it up and enhances its touch of a living thingand entertaining characteristics.

Appealing the loveliness and interest of such a pet robot using itsaction increases the user's affection for, and curiosity about, therobot and further enhances its entertaining characteristics.

DISCLOSURE OF THE INVENTION

The present invention, made in the light of the foregoing, proposes arobot which can enhance entertaining characteristics.

To solve this problem, a walking-on-four-legs type robot of the presentinvention whose body is connected at the front right, front left, rearright, and rear left with legs is provided with driving means fordriving the legs separately from each other and controlling means forcontrolling the driving means, the controlling means being adapted tocontrol the driving means so that when the robot tumbles sideward, thedriving means turns the forelegs and hind legs under the body in suchdirections that the legs open apart from each other and then turns thelegs in such directions that they move away from the body. Thus becausethe robot can stand up by itself after it falls down, the user's work ofstanding it up is eliminated, and its touch of a living thing isincreased, so that entertaining characteristics can be enhanced.

A walking-on-four-legs type robot of the present invention whose body isconnected at the front right, front left, rear right, and rear left withlegs is provided with driving means for driving the legs separately fromeach other and controlling means for controlling the driving means, thecontrolling means being adapted to control the driving means so thatwhen the robot tumbles forward, the driving means turns the legs at thefront of the body until they are almost parallel in front of the bodyand then turns the legs toward the rear of the body. Thus because therobot can stand up by itself after it falls down, the user's work ofstanding it up is eliminated, and its touch of a living thing isincreased, so that entertaining characteristics can be enhanced.

A walking-on-four-legs type robot of the present invention whose body isconnected at the front right, front left, rear right, and rear left withlegs is provided with driving means for driving the legs separately fromeach other and controlling means for controlling the driving means, thecontrolling means being adapted to control the driving means so thatwhen the robot tumbles backward, the driving means turns the legs at therear of the body in such directions that the legs move away from thebody until they are almost straight and then turns the legs toward thefront of the body. Thus because the robot can stand up by itself afterit falls down, the user's work of standing it up is eliminated, and itstouch of a living thing is increased, so that entertainingcharacteristics can be enhanced.

A walking-on-four-legs type robot of the present invention whose body isconnected at the front right, front left, rear right, and rear left withlegs is provided with driving means for driving the legs separately fromeach other and controlling means for controlling the driving means, thecontrolling means being adapted to control the driving means so that thedriving means opens the legs radially and then bends the legs above thebody. The resulting motion represents a touch of a robot, thus enhancingentertaining characteristics.

A walking-on-four-legs type robot of the present invention whose body isconnected at the front right, front left, rear right, and rear left withlegs and provided at the front with a head is provided with drivingmeans for driving the legs and head separately from each other andcontrolling means for controlling the driving means, the controllingmeans being adapted to control the driving means so that the end of aleg under the body moves up and down at the back of the head. Theresulting motion allows the robot to appear to scratch the back of itshead, thus appealing a touch of a living thing and enhancingentertaining characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an arrangement of a pet robot ofthe embodiment.

FIG. 2 is a perspective view showing an arrangement of a pet robot ofthe embodiment.

FIG. 3 is a block diagram illustrating processing by a controller.

FIG. 4 is a conceptual view illustrating a probability automaton.

FIG. 5 is a conceptual view illustrating a condition transition table.

FIG. 6 is a schematic diagram illustrating a pet robot motion.

FIG. 7 is a schematic diagram illustrating the pet robot motion.

FIG. 8 is a schematic diagram illustrating the pet robot motion.

FIG. 9 is a schematic diagram illustrating the pet robot motion.

FIG. 10 is a schematic diagram illustrating the pet robot motion.

FIG. 11 is a schematic diagram illustrating the pet robot motion.

FIG. 12 is a schematic diagram illustrating the pet robot motion.

FIG. 13 is a schematic diagram illustrating the pet robot motion.

FIG. 14 is a schematic diagram illustrating the pet robot motion.

FIG. 15 is a schematic diagram illustrating the pet robot motion.

FIG. 16 is a schematic diagram illustrating the pet robot motion.

FIG. 17 is a schematic diagram illustrating the pet robot motion.

FIG. 18 is a schematic diagram illustrating the pet robot motion.

FIG. 19 is a schematic diagram illustrating the pet robot motion.

FIG. 20 is a schematic diagram illustrating the pet robot motion.

FIG. 21 is a schematic diagram illustrating the pet robot motion.

FIG. 22 is a schematic diagram illustrating the pet robot motion.

FIG. 23 is a schematic diagram illustrating the pet robot motion.

FIG. 24 is a schematic diagram illustrating the pet robot motion.

FIG. 25 is a schematic diagram illustrating the pet robot motion.

FIG. 26 is a schematic diagram illustrating the pet robot motion.

FIG. 27 is a schematic diagram illustrating the pet robot motion.

FIG. 28 is a schematic diagram illustrating the pet robot motion.

FIG. 29 is a schematic diagram illustrating the pet robot motion.

FIG. 30 is a schematic diagram illustrating the pet robot motion.

FIG. 31 is a schematic diagram illustrating the pet robot motion.

FIG. 32 is a schematic diagram illustrating the pet robot motion.

FIG. 33 is a schematic diagram illustrating the pet robot motion.

FIG. 34 is a schematic diagram illustrating the pet robot motion.

FIG. 35 is a schematic diagram illustrating the pet robot motion.

FIG. 36 is a schematic diagram illustrating the pet robot motion.

FIG. 37 is a schematic diagram illustrating the pet robot motion.

FIG. 38 is a schematic diagram illustrating the pet robot motion.

FIG. 39 is a schematic diagram illustrating the pet robot motion.

FIG. 40 is a schematic diagram illustrating the pet robot motion.

FIG. 41 is a schematic diagram illustrating the pet robot motion.

FIG. 42 is a schematic diagram illustrating the pet robot motion.

FIG. 43 is a schematic diagram illustrating the pet robot motion.

FIG. 44 is a schematic diagram illustrating the pet robot motion.

FIG. 45 is a schematic diagram illustrating the pet robot motion.

FIG. 46 is a schematic diagram illustrating the pet robot motion.

FIG. 47 is a schematic diagram illustrating the pet robot motion.

FIG. 48 is a schematic diagram illustrating the pet robot motion.

FIG. 49 is a schematic diagram illustrating the pet robot motion.

FIG. 50 is a schematic diagram illustrating the pet robot motion.

FIG. 51 is a schematic diagram illustrating the pet robot motion.

FIG. 52 is a schematic diagram illustrating the pet robot motion.

FIG. 53 is a schematic diagram illustrating the pet robot motion.

FIG. 54 is a schematic diagram illustrating the pet robot motion.

FIG. 55 is a schematic diagram illustrating the pet robot motion.

FIG. 56 is a schematic diagram illustrating the pet robot motion.

FIG. 57 is a schematic diagram illustrating the pet robot motion.

FIG. 58 is a schematic diagram illustrating the pet robot motion.

FIG. 59 is a schematic diagram illustrating the pet robot motion.

FIG. 60 is a schematic diagram illustrating the pet robot motion.

FIG. 61 is a schematic diagram illustrating the pet robot motion.

FIG. 62 is a schematic diagram illustrating the pet robot motion.

FIG. 63 is a schematic diagram illustrating the pet robot motion.

FIG. 64 is a schematic diagram illustrating the pet robot motion.

FIG. 65 is a schematic diagram illustrating the pet robot motion.

FIG. 66 is a schematic diagram illustrating the pet robot motion.

FIG. 67 is a schematic diagram illustrating the pet robot motion.

FIG. 68 is a schematic diagram illustrating the pet robot motion.

FIG. 69 is a schematic diagram illustrating the pet robot motion.

FIG. 70 is a schematic diagram illustrating the pet robot motion.

FIG. 71 is a schematic diagram illustrating the pet robot motion.

FIG. 72 is a schematic diagram illustrating the pet robot motion.

FIG. 73 is a schematic diagram illustrating the pet robot motion.

FIG. 74 is a schematic diagram illustrating the pet robot motion.

FIG. 75 is a schematic diagram illustrating the pet robot motion.

FIG. 76 is a schematic diagram illustrating the pet robot motion.

FIG. 77 is a schematic diagram illustrating the pet robot motion.

FIG. 78 is a schematic diagram illustrating the pet robot motion.

FIG. 79 is a schematic diagram illustrating the pet robot motion.

FIG. 80 is a schematic diagram illustrating the pet robot motion.

FIG. 81 is a schematic diagram illustrating the pet robot motion.

FIG. 82 is a schematic diagram illustrating the pet robot motion.

FIG. 83 is a schematic diagram illustrating the pet robot motion.

FIG. 84 is a schematic diagram illustrating the pet robot motion.

FIG. 85 is a schematic diagram illustrating the pet robot motion.

FIG. 86 is a schematic diagram illustrating the pet robot motion.

FIG. 87 is a schematic diagram illustrating the pet robot motion.

FIG. 88 is a schematic diagram illustrating the pet robot motion.

FIG. 89 is a schematic diagram illustrating the pet robot motion.

FIG. 90 is a schematic diagram illustrating the pet robot motion.

FIG. 91 is a schematic diagram illustrating the pet robot motion.

FIG. 92 is a schematic diagram illustrating the pet robot motion.

FIG. 93 is a schematic diagram illustrating the pet robot motion.

FIG. 94 is a schematic diagram illustrating the pet robot motion.

FIG. 95 is a schematic diagram illustrating the pet robot motion.

FIG. 96 is a schematic diagram illustrating the pet robot motion.

FIG. 97 is a schematic diagram illustrating the pet robot motion.

FIG. 98 is a schematic diagram illustrating the pet robot motion.

FIG. 99 is a schematic diagram illustrating the pet robot motion.

FIG. 100 is a schematic diagram illustrating the pet robot motion.

FIG. 101 is a schematic diagram illustrating the pet robot motion.

FIG. 102 is a schematic diagram illustrating the pet robot motion.

FIG. 103 is a schematic diagram illustrating the pet robot motion.

FIG. 104 is a schematic diagram illustrating the pet robot motion.

FIG. 105 is a schematic diagram illustrating the pet robot motion.

FIG. 106 is a schematic diagram illustrating the pet robot motion.

FIG. 107 is a schematic diagram illustrating the pet robot motion.

FIG. 108 is a schematic diagram illustrating the pet robot motion.

FIG. 109 is a schematic diagram illustrating the pet robot motion.

FIG. 110 is a schematic diagram illustrating the pet robot motion.

FIG. 111 is a schematic diagram illustrating the pet robot motion.

FIG. 112 is a schematic diagram illustrating the pet robot motion.

FIG. 113 is a schematic diagram illustrating the pet robot motion.

FIG. 114 is a schematic diagram illustrating the pet robot motion.

FIG. 115 is a schematic diagram illustrating the pet robot motion.

FIG. 116 is a schematic diagram illustrating the pet robot motion.

FIG. 117 is a schematic diagram illustrating the pet robot motion.

FIG. 118 is a schematic diagram illustrating the pet robot motion.

FIG. 119 is a schematic diagram illustrating the pet robot motion.

FIG. 120 is a schematic diagram illustrating the pet robot motion.

FIG. 121 is a schematic diagram illustrating the pet robot motion.

FIG. 122 is a schematic diagram illustrating the pet robot motion.

FIG. 123 is a schematic diagram illustrating the pet robot motion.

FIG. 124 is a schematic diagram illustrating the pet robot motion.

FIG. 125 is a schematic diagram illustrating the pet robot motion.

FIG. 126 is a schematic diagram illustrating the pet robot motion.

FIG. 127 is a schematic diagram illustrating the pet robot motion.

FIG. 128 is a schematic diagram illustrating the pet robot motion.

FIG. 129 is a schematic diagram illustrating the pet robot motion.

FIG. 130 is a schematic diagram illustrating the pet robot motion.

FIG. 131 is a schematic diagram illustrating the pet robot motion.

FIG. 132 is a schematic diagram illustrating the pet robot motion.

FIG. 133 is a schematic diagram illustrating the pet robot motion.

FIG. 134 is a schematic diagram illustrating the pet robot motion.

FIG. 135 is a schematic diagram illustrating the pet robot motion.

FIG. 136 is a schematic diagram illustrating the pet robot motion.

FIG. 137 is a schematic diagram illustrating the pet robot motion.

FIG. 138 is a schematic diagram illustrating the pet robot motion.

FIG. 139 is a schematic diagram illustrating the pet robot motion.

FIG. 140 is a schematic diagram illustrating the pet robot motion.

FIG. 141 is a schematic diagram illustrating the pet robot motion.

FIG. 142 is a schematic diagram illustrating the pet robot motion.

FIG. 143 is a schematic diagram illustrating the pet robot motion.

FIG. 144 is a schematic diagram illustrating the pet robot motion.

FIG. 145 is a schematic diagram illustrating the pet robot motion.

FIG. 146 is a schematic diagram illustrating the pet robot motion.

FIG. 147 is a schematic diagram illustrating the pet robot motion.

FIG. 148 is a schematic diagram illustrating the pet robot motion.

FIG. 149 is a schematic diagram illustrating the pet robot motion.

FIG. 150 is a schematic diagram illustrating the pet robot motion.

FIG. 151 is a schematic diagram illustrating the pet robot motion.

FIG. 152 is a schematic diagram illustrating the pet robot motion.

FIG. 153 is a schematic diagram illustrating the pet robot motion.

FIG. 154 is a schematic diagram illustrating the pet robot motion.

FIG. 155 is a schematic diagram illustrating the pet robot motion.

FIG. 156 is a schematic diagram illustrating the pet robot motion.

FIG. 157 is a schematic diagram illustrating the pet robot motion.

FIG. 158 is a schematic diagram illustrating the pet robot motion.

FIG. 159 is a schematic diagram illustrating the pet robot motion.

FIG. 160 is a schematic diagram illustrating the pet robot motion.

FIG. 161 is a schematic diagram illustrating the pet robot motion.

FIG. 162 is a schematic diagram illustrating the pet robot motion.

FIG. 163 is a schematic diagram illustrating the pet robot motion.

FIG. 164 is a schematic diagram illustrating the pet robot motion.

FIG. 165 is a schematic diagram illustrating the pet robot motion.

FIG. 166 is a schematic diagram illustrating the pet robot motion.

FIG. 167 is a schematic diagram illustrating the pet robot motion.

FIG. 168 is a schematic diagram illustrating the pet robot motion.

FIG. 169 is a schematic diagram illustrating the pet robot motion.

FIG. 170 is a schematic diagram illustrating the pet robot motion.

FIG. 171 is a schematic diagram illustrating the pet robot motion.

FIG. 172 is a schematic diagram illustrating the pet robot motion.

FIG. 173 is a schematic diagram illustrating the pet robot motion.

FIG. 174 is a schematic diagram illustrating the pet robot motion.

FIG. 175 is a schematic diagram illustrating the pet robot motion.

FIG. 176 is a schematic diagram illustrating the pet robot motion.

FIG. 177 is a schematic diagram illustrating the pet robot motion.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings, an embodiment of the present inventionwill be described in detail below.

(1) Arrangement of Pet Robot 1 According to the Embodiment

In FIG. 1, a reference numeral 1 generally indicates a pet robotaccording to the embodiment, which robot is arranged by connecting legs3A through 3D to a body 2 at its front right, front left, rear right,and rear left, a head 4 to the front end of the body 2, and a tail 5 tothe rear end of the body 2.

As shown in FIG. 2, the body 2 contains a controller 10 which controlsall actions of the pet robot 1, a battery 11 serving as a power sourcefor the pet robot 1, an internal sensor unit 14 consisting of a batterysensor 11, an angular velocity sensor 12, an acceleration sensor 13,etc., and the like.

The head 4 is provided in predetermined positions with a microphone 16functioning as the ears of the pet robot 1, an external sensor unit 19functioning as the eyes which consists of a CCD (charge coupled device)camera 17, a touch sensor 18, etc., a speaker 20 functioning as a mouth,a mouth member 21 functioning as the apparent mouth of the pet robot 1,LEDs (light-emitting diodes), not shown, functioning as the apparenteyes, and the like.

Lap joint mechanisms 22A through 22D which connect thighs 3AX through3DX and shanks 3AY through 3DY together in the legs 3A through 3D,shoulder joint mechanisms 23A through 23D which connect the legs 3Athrough 3D and the body 2 together, a neck joint mechanism 24 whichconnects the body 2 and head 4 together, a chin joint mechanism 25 whichopens or closes the mouth member 21, a tail joint mechanism 26 whichconnects the body 2 and tail 5 together are provided with as manyactuators 27 ₁ through 27 ₁₈ as degrees of freedom required.

The microphone 16 in the external sensor unit 19 collects sound of thedirections “Walk,” “Lie down,” “Follow the ball,” etc. given as scalesthrough a sound commander, not shown, by the user and transmits an audiosignal S1A obtained to a controller 10. The CCD camera 17 shootssurrounding scenes and transmits a visual signal S1B obtained to thecontroller 10.

As is clear from FIG. 1, the touch sensor 18 is provided on top of thehead 4. The sensor detects pressure due to the user's physical actions,such as stroking and patting, and transmits the result as a pressuredetection signal S1C to the controller 10.

The battery sensor 12 in the internal sensor unit 15 detects the amountof residual charge in the battery 11 and transmits the result as abattery residual charge detection signal S2A to the controller 10. Theangular velocity sensor 13 detects angular velocity for three axes (x,y, and z) and transmits the result as an angular velocity detectionsignal S2B to the controller 10. The acceleration sensor 14 detectsacceleration for the three axes (x, y, and z) and transmits the resultas an acceleration detection signal S2C to the controller 10.

Based on the audio signal S1A, visual signal S1B, and pressure detectionsignal S1C (these signals are hereinafter called external sensor signalsS1 collectively) fed from the microphone 16, CCD camera 17, and touchsensor 18 in the external sensor unit 19, respectively, and the batteryresidual charge detection signal S2A, angular velocity detection signalS2B, and acceleration detection signal S2C (these signals arehereinafter called internal sensor signals S2 collectively) fed from thebattery sensor 12, angular velocity sensor 13, and acceleration sensor14 in the internal sensor unit 15, the controller 10 determines thesituation around and in the pet robot 1 and whether the user acts towardthe robot.

Based on the results of determination and a control program stored inmemory 10A, the controller 10 determines an action which the robot is toperform and drives actuators 27 ₁ through 27 _(n) according to theaction to make the robot perform actions, such as vertically andhorizontally swinging the head 4, wagging the tail 5, walking on thelegs 3A through 3D.

The controller 10 feeds a predetermined audio signal S3 to the speaker20 as required to output sound based on the audio signal S3 and flash onand off the LEDs as the apparent eyes.

As described above, the pet robot 1 is adapted to independently actbased on the surrounding environment, its own condition, and a directionfrom the user or his or her action.

The lap joint mechanisms 22A through 22D in the legs 3A through 3D ofthe pet robot 1 has a degree of freedom of rotation about a pitch axisparallel to an arrow yin FIG. 1, and the shoulder joint mechanisms 23Athrough 23D freely rotate about the pitch axis parallel to the arrow yin FIG. 1 and a roll axis parallel to an arrow x in FIG. 1.

This allows the pet robot 1 to move the laps in the legs 3A through 3Din forward and backward directions (the forward direction is indicatedby the arrow x) within a predetermined range and the entire legs 3Athrough 3D in the forward and backward directions and rightward andleftward directions (the leftward direction is indicated by the arrow y)within predetermined ranges.

The neck joint mechanism 24 of the pet robot 1 freely rotates about theroll axis parallel to the arrow x, the pitch axis parallel to the arrowy, and a yaw axis parallel to an arrow z in FIG. 1. This allows the head2 to move in the forward, backward, rightward, and leftward directionsand an inclination direction within predetermined ranges.

The tail joint mechanism 26 of the pet robot 1 freely rotates about theroll axis parallel to the arrow x and the yaw axis parallel to the arrowz. This allows the tail 5 to move in the forward, backward, rightward,and leftward directions within predetermined ranges.

(2) Processing by the Controller 10

Processing by the controller 10, related to generation of action of thepet robot 1, will be specifically described below.

As shown in FIG. 3, basic processing steps performed by the controller10, which are related to generation of action of the pet robot 1, can befunctionally assigned to a condition recognizing mechanism 30 whichrecognizes condition, an emotion/instinct modeling unit 31 whichdetermines the emotional and instinctive condition of the pet robot 1based on recognition by the condition recognizing mechanism 30, abehavior determining mechanism 32 which determines an action based onrecognition by the condition recognizing mechanism 30 and emotion andinstinct modeled by the emotion/instinct modeling unit 31, and abehavior generating mechanism 33 which makes the pet robot 1 behave oract based on determination by the behavior determining mechanism 32.

Based on the external information signals S1 from the external sensorunit 19 (FIG. 2) and the internal information signals S2 from theinternal sensor unit 15, the condition recognizing mechanism 30recognizes the condition of surroundings and the pet robot and adirection from the user or his or her action and informs theemotion/instinct modeling unit 31 and behavior determining mechanism 32of the result of recognition as condition recognition information S10.

Specifically, when the condition recognizing mechanism 30, which keepsmonitoring audio signals 1A from, for example, the microphone 16 in theexternal sensor unit 19, detects scale sound corresponding to adirection, such as “Walk,” “Lie down,” or “Follow the ball,” itrecognizes the direction and informs the emotion/instinct modeling unit31 and behavior determining mechanism 32 of the recognition.

When the condition recognizing mechanism 30, which keeps monitoring animage signal S2A fed from the CCD camera 17, detects a red, round objector a vertical plane in an image based on the image signal S2A, themechanism recognizes that there is a ball or that there is a wall andinforms the emotion/instinct modeling unit 31 and behavior determiningmechanism 32 of the recognition.

When the condition recognizing mechanism 30, which keeps monitoring apressure detection signal S1B fed from the touch sensor 18, detects apressure higher than a predetermined threshold value based on thepressure detection signal S1B for a short time (for example, less thantwo seconds), the mechanism recognizes that the pet robot has beenslapped (or scolded) and informs the emotion/instinct modeling unit 31and behavior determining mechanism 32 of the recognition. On the otherhand, when the condition recognizing mechanism 30 detects a pressureless than the predetermined threshold value for a long time (forexample, two seconds or more), the mechanism recognizes that the petrobot has been stroked (or praised) and informs the emotion/instinctmodeling unit 31 and behavior determining mechanism 32 of therecognition.

When the condition recognizing mechanism 30, which keeps monitoring anangular velocity detection signal S2B fed from the angular velocitysensor 13 in the internal sensor unit 12, detects angular velocity inthe direction of the x, y, and/or z axis based on the angular velocitydetection signal S2B, the mechanism recognizes that the pet robot hasrotated or inclined in the direction and informs the emotion/instinctmodeling unit 31 and behavior determining mechanism 32 of therecognition.

When the condition recognizing mechanism 30, which keeps monitoring anacceleration detection signal S2C fed from the acceleration sensor 14,detects acceleration in the direction of the x, y, and/or z axis, themechanism recognizes that the pet robot has moved in the direction andinforms the emotion/instinct modeling unit 31 and behavior determiningmechanism 32 of the recognition.

The emotion/instinct modeling unit 31 has parameters which represent thestrength of six emotions, that is, joy, sadness, amazement, horror,disgust, and anger, one parameter for one emotion. The emotion/instinctmodeling unit 31 changes the values of the parameters one after another,based on recognition results provided as condition recognitioninformation S10 by the condition recognizing mechanism 30, behaviordetermining information S13, which represents determined output behaviorprovided by the behavior determining mechanism 32 as described later,elapsed time, etc.

Specifically, the emotion/instinct modeling unit 31 computes the valueE[t+1] of a parameter of an emotion for the next period at predeterminedtime intervals, using the following equation:

E[t+1]=E[t]+k_(e)×ΔE[t]  (1)

where ΔE[t] is a change in the emotion computed from a predeterminedequation, based on the degree of effect of a recognition result obtainedbased on the condition recognition information 10 and output behaviorbased on the behavior determining information S13 on the emotion (thedegree is predetermined), the degree of restriction and stimulus byother emotions, elapsed time, etc., E[t] is the current value of theparameter of the emotion, and k_(e) is a coefficient representing a rateat which the emotion is changed according to the recognition result andthe like.

The emotion/instinct modeling unit 31 updates the current value E[t] ofthe parameter of the e emotion by replacing it with the result ofcomputation. The emotion of which parameter value should be updated foroutput behavior and a recognition result is predetermined. For example,when the emotion/instinct modeling unit recognizes that the pet robothas been slapped, the value of the parameter of anger increases whilethat of the parameter of joy decreases. When the modeling unitrecognizes that the pet robot has been stroked, the value of theparameter of the joy increases while that of the value of sadnessdecreases.

Similarly, the emotion/instinct modeling unit 31 has parameters whichrepresent the strength of desires independent of each other, that is, adesire for exercise, a desire for affection, appetite, and curiosity,one parameter for one desire. The emotion/instinct modeling unit 31updates the values of the parameters of these desires one after anotherbased on recognition by the condition recognizing mechanism 30, elapsedtime, information from the behavior determining mechanism 32, and thelike.

Specifically, the emotion/instinct modeling unit 31 computes the valueI[k+1] of a parameter of a desire, that is, a desire for exercise, adesire for affection, or curiosity, for the next period at predeterminedtime intervals, using the following equation:

I[k+1]=I[k]+k_(i)×ΔI[k]  (2)

where ΔI[k] is a change in the desire computed from a predeterminedequation, based on output behavior of the pet robot 1, elapsed time, theresult of recognition, etc., I[k] is the current value of the parameterof the desire, and k_(i) is a coefficient which represents thesensitivity of the desire. The emotion/instinct modeling unit 31 updatesthe current value I[k] of the parameter of the emotion by replacing itwith the result of computation. The desire of which parameter valueshould be changed for a recognition result and output behavior ispredetermined. For example, when the behavior determining mechanism 32informs the modeling unit that some action has been taken, the value ofthe parameter of a desire for exercise decreases.

Based on a battery residual charge detection signal S2A (FIG. 2)provided through the condition recognizing mechanism 30, theemotion/instinct modeling unit 31 computes the value I[k+1] of theparameter of appetite from the following equation at a predeterminedtime interval:

I[k]=100−B_(L)  (3)

where B_(L) is the amount of residual charge in the battery. Theemotion/instinct modeling unit 31 updates the current value I[k] of theparameter of the apetite by replacing it with the result of computation.

In the embodiment, the values of the parameters of the emotions anddesires are restricted to range from 0 to 100, and the values of k_(e)and k_(i) are set for each emotion and each desire.

The behavior determining mechanism 32 determines the next action, basedon condition recognition information S10 fed from the conditionrecognizing mechanism 30, the values of the parameters of the emotionsand desires computed by the emotion/instinct modeling unit 31, an actionmodel stored in the memory 10A, elapsed time, etc. And outputs theresult of determination as behavior determining information S12 to theemotion/instinct modeling unit 31 and behavior generating mechanism 33.

To determine the next action, the behavior determining mechanism 32 usesan algorithm, called probability automaton, which determines on aprobability basis which of nodes NODE₀ through NODE_(n) the pet robottransits from the node NODE₀ to as shown in FIG. 4, based on transitionprobabilities P₀ through P_(n) set for arcs ARC₀ through ARC_(n)connecting the nodes NODE₀ through NODE_(n) with each other.

Specifically, the behavior determining mechanism 32 is intended todetermine the next action based on a state transition table 40 which isstored as an action model for each of the nodes NODE₀ through NODE_(n)in the memory 10A as shown in FIG. 5.

In the state transition table 40, input events (results of recognitionby the condition recognizing mechanism 30), transition requirements forthe nodes NODE₀ through NODE_(n), are listed on an input event line inorder of priority, and requirements accompanying the transitionrequirements are described in corresponding rows in data name and datarange lines.

For the node NODE₁₀₀ defined in the state transition table 40 in FIG. 5,when a recognition is provided that a ball (BALL) has been detected, thesize (SIZE) of the ball, provided together with the recognition, isrequired to range from 0 to 1000 (0, 1000), and when a recognition isprovided that an obstacle (OBSTACLE) has been detected, the distance(DISTANCE) to the obstacle, provided together with the recognition, isrequired to range from 0 to 1000 (0, 1000) in order to transit to thenode or other nodes.

For the node NODE₁₀₀ also, even when no recognition is input, it ispossible to transit to the node or other nodes if any of the parametersof emotions of joy (JOY), surprise (SURPRISE), and sadness (SUDNESS) inthe emotion/instinct modeling unit 31, which parameters are periodicallyreferred to by the behavior determining mechanism 32, ranges in valuefrom 50 to 1000 (50, 1000).

In the state transition table 40, the names of nodes to which the petrobot can transit from the nodes NODE₀ through NODE_(n) are listed inthe destination node row in the column under “Probability of transitionto other nodes,” and the probability of transition to the nodes NODE₀through NODE_(n) as provided when all requirements described on theinput event name, data value, and data range lines are met is written onthe lines for the nodes NODE₀ through NODE_(n) in the column under“Probability of transition to other nodes,” and behavior or action whichis output at that time is described on the output behavior line. The sumof the probabilities written on the lines in the column under“Probability of transition to other nodes” is 100%.

Thus for the node NODE₁₀₀, when a recognition is provided that a ball(BALL) has been detected and that the size (SIZE) of the ball rangesfrom 0 to 1000 (0, 1000), the pet robot can transit to the node NODE₁₂₀(node 120) with a probability of 30%. When the robot transits to thenode, behavior or action ACTION 1 is output.

A behavior model is arranged so that the nodes NODE₀ through NODE_(n)written in the form of the state transition table 40 succeed.

As described above, when the state recognition mechanism 30 provides thestate recognition information S10, or a certain time has elapsed afterthe last behavior is exhibited, the behavior determining mechanism 32determines the next behavior or action (behavior or action described onthe output behavior line) on a probability basis, using the statetransition table 40 for the nodes NODE₀ through NODE_(n) whichcorresponds to a behavior model stored in the memory 10A and outputs theresult of determination as the behavior determination information S12 tothe emotion/instinct modeling unit 31 and behavior generating mechanism33.

On the other hand, based on the behavior determination information S13provided by the behavior determining mechanism 32, the behaviorgenerating mechanism 33 transmits a driving signal S14 (S14 ₁ throughS14 ₁₈) to necessary actuators 27 ₁ through 27 ₁₈ (FIG. 2), a necessaryaudio signal S3 to the speaker 20 (FIG. 2), or an LED driving signal S15to the LEDs serving as the eyes.

As a result, the behavior generating mechanism 33 drives the necessaryactuators 27 ₁ through 27 ₁₈ so that a predetermined condition is met,based on the driving signal S14; makes the speaker 20 output sound basedon the audio signal S3, or flashes the LEDs on and off according to aflash-on and -off pattern based on the LED driving signal S15.

As described above, based on condition outside or inside the pet robot1, whether the user acts toward the pet robot 1, etc., the controller 10makes the pet robot 1 behave independently.

3) Motions of the Pet Robot 1

Motions of the pet robot 1 will be described below. The pet robot 1 isintended to present a touch of a living thing and a robot through itsmotions.

Motions of the pet robot 1 can be classified into the following types:tumble recovery, or standing up after a tumble; robot, or behaving likea robot; dog, or behaving like a dog; ball response, or behavior asobserved when the robot finds a ball; emotion expression, or expressingemotion; idleness, or behavior as observed when the robot is idle;language, or conveying will to the user; and the like.

By example, these types of motions will be described below.

(3-1) Tumble recovery motions

Motions which the pet robot 1 makes to stand up when it tumbles (tumblerecovery motion) and motions which the pet robot 1 makes after tumblerecovery (post-tumble-recovery motion) will be described below.

(3-1-1) First tumble recovery motion

First, a tumble recovery motion which the pet robot 1 makes when ittumbles to the left as shown in FIG. 6A will be described below.

When it tumbles leftward, the pet robot 1 first straightens the left andright forelegs 3A and 3B and left and right hind legs 3C and 3D as shownin FIG. 6A to take a basic upright position and then turns the leftforeleg 3A and left hind leg 3C, which are on the underside due to atumble, in such directions that the legs open apart from each other, asshown in FIGS. 6B through 6D. In addition to this leg opening motion,the pet robot 1 turns the shank 3AY (FIG. 1) toward the rear to bend-theleft foreleg 3A backward and turns the shank 3CY (FIG. 1) toward thefront to bend the left hind leg 3C forward.

When the pet robot 1 has opened the left foreleg 3A and left hind leg 3Capart to the extent that the thigh 3AX (FIG. 1) in the left foreleg 3Aand the thigh 3CY (FIG. 1) in the left hind leg 3C are almost parallelto each other as shown in FIG. 6D, the robot turns the left foreleg 3Aand left hind leg 3C outside. As a result, the pet robot 1 turns as awhole as shown in FIGS. 6E and 6F so that the stomach of the body 2comes in contact with the floor, and the right foreleg 3B and right hindleg 3D, which are on the upside due to the fall, come in contact withthe floor. Then by turning the left foreleg 3A and left hind leg 3C insuch directions that the legs close together, as shown in FIGS. 7B and7C, the pet robot 1 brings the left foreleg 3A and left hind leg 3Cclose to the body 2 to take the basic upright position.

Then the pet robot 1 straightens the bent right and left forelegs 3B and3A as shown in FIGS. 7D, 8A, and 8B to stand up in the basic uprightposition, while slightly moving the center of gravity forward bystraightening the bent right and left hind legs 3D and 3C. This ends themotion.

(3-1-2) Second tumble recovery motion

Next, a tumble recovery motion which the pet robot 1 makes when ittumbles forward as shown in FIG. 9A will be described below.

When it tumbles forward, the pet robot 1 turns the right and leftforelegs 3B and 3A in such directions that the legs open apart, as shownin FIGS. 9B through 9D, and further turns the right and left forelegs 3Band 3A about their pitch axes to direct toward the floor the contactsurfaces provided by the bottoms of the ends of the legs.

Next, as shown in FIGS. 9E, 9F, and 10A, the pet robot 1 turns the rightand left forelegs 3B and 3A in such directions that the legs closetogether, while arching the right and left forelegs 3B and 3A so thattheir contact surfaces do not come in contact with the floor.

When this leg closing motion closes the hind right fore leg 3D and leftforeleg 3A until the legs are almost parallel to each other as shown inFIG. 10A, the pet robot 1 brings the right and left forelegs 3B and 3Aclose to the body 2 by turning the right and left forelegs 3B and 3A insuch directions that the right foreleg 3B and left foreleg 3A come closeto the right and left hind legs 3D and 3C, respectively, while slightlybending the right and left hind legs 3 and 3C to take a lower position.

Then the pet robot 1 gradually straightens the bent right and leftforelegs 3B and 3A and right and left hind legs 3D and 3C to stand up inthe basic upright position. This ends the motion.

(3-1-3) Third tumble recovery motion

Next, a tumble recovery motion which the pet robot 1 makes when ittumbles backward as shown in FIG. 11A will be described below.

When it tumbles backward, the pet robot 1 straightens the right and leftforelegs 3B and 3A and right and left hind legs 3D and 3C as shown inFIGS. 11A to take the basic upright position and then lifts the head 4(FIG. 2) forward as viewed from the pet robot 1, as shown in FIGS. 11Band 11C.

Next, as shown in FIGS. 11D through 11F, the pet robot 1 turns the rightand left forelegs 3B and 3A about their pitch axes to make the thighs3BX and 3AX in them parallel to the direction of gravity, while turningthe right and left hind legs 3D and 3C in such directions that the legsopen apart until they are almost parallel to each other. This causes thepet robot 1 to gradually tumble forward under the action of gravity.

When the right and left hind legs 3D and 3C open apart until the legsare almost parallel to each other, as shown in FIG. 12A, and the rightand left forelegs 3B and 3A come in contact with the floor, the petrobot 1 turns the right and left hind legs 3D and 3C in such directionsthat the legs close together, while bending them, as shown in FIGS. 12Bthrough 12F.

Then when the pet robot 1 closes the right and left hind legs 3D and 3Ctogether until they are almost parallel to each other, as shown in FIG.13A, the robot brings the right and left hind legs 3D and 3C close tothe body 2 by turning these legs in such directions that the right andleft hind legs 3D and 3C come close to the right foreleg 3B and leftforeleg 3A, respectively and then straightens the bent right and lefthind legs 3D and 3C to take the basic upright position. This ends themotion.

(3-1-4) First post-tumble-recovery motion

Next, a motion which the pet robot 1 makes will be described below.

When the pet robot 1 takes the basic upright position with the tumblerecovery motion described above as shown in FIG. 14A, it moves thecenter of gravity to prevent its weight from acting on the left foreleg3A (or the right foreleg 3B) and then lifts the left foreleg 3A (or theright foreleg 3B) by turning forward, as shown in FIGS. 14C through 14F.The pet robot 1 turns the thigh 3AY (3BY) in the left foreleg 3A (or theright foreleg 3B) toward the rear to bend the left foreleg 3A (or theright foreleg 3B). In addition, the pet robot 1 turns the head 4 througha predetermined angle to the right (or the left) as viewed from the petrobot 1.

Then when the contact surface of the left foreleg 3A (or the rightforeleg 3B) comes close to the back of the head 4 as shown in FIG. 15A,the pet robot 1 turns the shank 3AY (3BY) in the left foreleg 3A (or theright foreleg 3B) through a predetermined angle a few times toward thefront and rear of the pet robot 1.

After this action is completed, the pet robot performs the reverse ofthe actions shown in FIGS. 14A through 14F to return to the uprightposition. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 scratches theback of the head 4 in embarrassment because it tumbles, thus giving theuser a lovely impression.

(3-1-5) Second post-tumble-recovery motion

Next, a second post-tumble-recovery motion which the pet robot 1 makeswill be described below.

After it takes the basic upright position with the tumble recoverymotion described above as shown in FIG. 17A, the pet robot 1 slightlybends the right and left forelegs 3B and 3A and right and left hind legs3D and 3C as shown in FIG. 17B to take a lower position and turns thehead 4 toward its front as shown in FIG. 17C to direct the head 4downward.

Then the pet robot 1 turns the head 4 to the right and left a few timesas shown in FIGS. 17D through 18A. Next, the robot straightens the rightand left forelegs 3B and 3A and the right and left hind legs 3D and 3Cto return to the basic upright position. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 swings the head4 to the right and left to refresh, thus giving the user a lovelyimpression.

(3-1-6) Other tumble recovery motions

FIGS. 19A through 20F show the flow of a tumble recovery motion withwhich the pet robot 1 stands up after it tumbles rightward. The tumblerecovery motion is the same as the first tumble recovery motion exceptthat the former is opposite in direction to the latter.

(3-2) Robot language motions

Robotlike actions will be described below which the pet robot 1 performswhen the condition recognizing mechanism 30 (FIG. 3) in the controller10 (FIG. 2) does not provide a specific recognition result (such actionsare hereinafter called robot language motions).

(3-2-1) First robot language motion First, a first robot language motionwill be described below. When the pet robot 1 is in a basic downposition, it produces the first robot language motion.

When the pet robot 1 is in a down position, with the right and leftforelegs 3B and 3A extended toward its front, as shown in FIG. 21A, therobot turns the right and left forelegs 3B and 3A in such directionsthat the legs open apart, as shown in FIGS. 21B and 21C. In addition, asshown in FIGS. 21B through 21E, the pet robot 1 extends the right andleft hind legs 3D and 3C toward the front and then turns these legstoward its rear to radially extend them. As a result, the pet robot 1takes such a position that the right and left forelegs 3B and 3C andright and left hind legs 3A and 3D form a cross, as shown in FIG. 21F.When the right and left hind legs 3D and 3C open apart until they arealmost parallel to each other, the pet robot 1 turns the right and lefthind legs 3D and 3C approximately 180° about their pitch axes.

Then as shown in FIGS. 22A through 22E, the pet robot 1 lifts the rightand left forelegs 3B and 3A and the right and left hind legs 3D and 3Cabove itself, while bending these legs. In parallel, the pet robot 1bends the head 4 toward its rear to lift the head 4, opens the mouth,and lifts the tail 5 above itself to bend the entire body.

Then as shown in FIGS. 22F through 23D, the pet robot 1 performs thereverse of the actions in FIGS. 21F through 22E to return to itsoriginal position as shown in FIG. 23D. Next, the pet robot 1 performsthe same action as in FIGS. 21F through 23D twice or three times.

Then as shown in FIGS. 23E through 24C, the pet robot 1 performs thereverse of the actions in FIGS. 21A through 21E to return to the downposition. This ends the motion.

Such a motion shows a touch of a robot.

(3-2-2) Second robot language motion

Next, a second robot language motion will be described below. When thepet robot 1 is in a basic down position as shown in FIG. 25A, itproduces the second robot language motion.

When it is in the down position as shown in FIG. 25A, the pet robot 1acts as shown in FIGS. 25A through 27A as is the case with the firstrobot language motion illustrated in FIGS. 21A through 21F to take sucha position that the right foreleg 3B and the left hind leg 3C and theleft foreleg 3A and the right hind legs 3D form a cross, as shown inFIG. 27A.

Then as shown in FIGS. 27B through 28D, the pet robot 1 alternatelyturns a combination of the right foreleg 3B and the right hind leg 3Cand a combination of the left foreleg 3A and the right hind leg 3Dthrough a predetermined angle a few times so that the angle does notchange which is made by a straight line formed by the right foreleg 3Band the left hind leg 3C and one formed by the left foreleg 3A and theright hind leg 3D.

When the combination of the right foreleg 3B and the left hind leg 3Cand that of the left foreleg 3A and the right hind leg 3D takes theposition in FIG. 27A as shown in FIG. 28F after the action is completed,the pet robot 1 performs the reverse of the actions in FIGS. 25A through27A as shown in FIGS. 29A through 30B to return to the original downposition. This ends the motion.

Such a motion shows a touch of a robot.

(3-2-3) Third robot language motion

A third robot language motion will be described below. The pet robot 1produces the third robot language motion as performance in response to adirection from the user.

When it is in the basic down position as shown in FIG. 31A, the petrobot 1 slightly opens the right and left hind legs 3D and 3C apartoutside as shown in FIG. 31B and then lifts the right and left hind legs3D and 3C to the extent that the ends of these legs are a little abovethe shoulders as shown in FIGS. 31C through 31F.

Then as shown in FIGS. 32A through 32F, the pet robot 1 turns the rightand left hind legs 3D and 3C one after the other a plurality of times insuch directions that the legs open and close to swing the right and lefthind legs 3D and 3C a plurality of times.

After this action is completed, the pet robot 1 lowers the right andleft hind legs 3D and 3C until they are extended forward as shown inFIGS. 33A through 33C and then removes the legs inside to return to theoriginal down position. This ends the motion.

Such a motion shows a touch of a robot.

(3-2-4) Other robot language motions

FIGS. 34A through 35C, 36A through 37E, 38A through 39F, and 40A through42E show other robot language motions, that is, fourth, fifth, sixth,and seventh robot language motions, respectively.

(3-3) Dog motions

Next, doglike motions will be described below which the pet robot 1makes when the condition recognizing mechanism 30 (FIG. 3) in thecontroller 10 (FIG. 2) does not provide a specific recognition result(these motions are hereinafter called dog motions).

(3-3-1) First dog motion

A first dog motion will be described below. When the pet robot 1 is in abasic down position as shown in FIG. 43A, it produces the first dogmotion.

When it is in the down position, with the right and left forelegs 3B and3A extended forward as shown in FIG. 43A, the pet robot 1 slightly movesthe left hind leg 3C (or the right hind leg 3D) outside as shown inFIGS. 43B and 43C to open it and then lifts the left hind leg 3C (or theright hind leg 3D) as shown in FIGS. 43D through 43F. In parallel, thepet robot 1 turns the head 4 to direct it off to the upper right forward(or off to the upper left forward).

Then when the contact surface of the left hind leg 3C (or the right hindleg 3D) has risen to the back of the head 4, the pet robot 1 verticallyturns the left hind leg 3C (or the right hind leg 3D) twice or threetimes as shown in FIGS. 43F through 44C to scratch the back of the head4 with the left hind leg 3C (or the right hind leg 3D).

Next, the pet robot lowers the left hind leg 3C (or the right hind leg3D) as shown in FIGS. 44D through 44F and then moves the left hind leg3C (or the right hind leg 3D) to return it inside, thus taking theoriginal down position. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 scratches theback of the head 4, thus giving the user a doglike impression.

(3-3-2) Second dog motion

Next, a second dog motion will be described below. When the pet robot 1is in an upright position as shown in FIG. 46A, it produces the seconddog motion.

As shown in FIG. 46B, the pet robot 1 moves the center of gravity sothat its weight does not act on the right hind leg 3D (or the left hindleg 3C). Next, the pet robot 1 slightly moves the right hind leg 3D (orthe left hind leg 3C) outside to open the leg and then lifts the righthind leg 3D (or the left hind leg 3C) above the robot itself. When doingso, the pet robot 1 bends the knee 3DY (or 3CY) in the right hind leg 3D(or the left hind leg 3C) to the extent that the thighs 3DX (or 3CY) andshank 3DY (or 3CY) are at right angles to each other.

After sound of running water is output from the speaker 20 (FIG. 2) fortwo to three seconds, the pet robot 1 performs the reverse of theactions in FIGS. 46A through 47A as shown in FIGS. 47B through 47E totake the original upright position. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 piddles, thusgiving the user a doglike impression.

(3-3-3) Other dog motions

FIGS. 48A through 51C, 52A through 54A, 55A through 58A, and 59A through61C show the flow of other dog motions, that is, third, fourth, fifth,and sixth dog motions, respectively.

(3-4) Ball response motions

Motions which the pet robot 1 produces when it finds a fall will bedescribed below (these motions are hereinafter called ball responsemotions).

(3-4-1) First ball response motion

A first ball response motion will be described below. When the pet robot1 finds a ball, it produces the first ball response motion.

When it finds a ball, the pet robot 1 walks close to the ball to theextent that the ball is just in front of the left foreleg 3A (or theright foreleg 3B) and then takes an upright position as shown in FIG.62A.

Next, as shown in FIG. 62B, the pet robot 1 moves the center of gravityso that its weight does not act on the left foreleg 3A (or the rightforeleg 3B) and then turns the left foreleg 3A (or the right foreleg 3B)through a predetermined angle toward the rear as shown in FIGS. 62Cthrough 62F to bring the left foreleg 3A (or the right foreleg 3B) closeto the left hind leg 3C (or the right hind leg 3D). In parallel, the petrobot 1 inclines the head 4 toward a position just in front of the leftforeleg 3A (or the right foreleg 3B) as if to look at the ball.

The pet robot 1 dynamically turns the left foreleg 3A (or the rightforeleg 3B) toward the front, while extending the withdrawn left foreleg3A (or right foreleg 3B), as shown in FIGS. 63A through 63D. Next, asshown in FIGS. 63E through 64B, the pet robot 1 lowers the left foreleg3A (or the right foreleg 3B) to return it to the original position andthen straightens the bent right foreleg 3B (or left foreleg 3A), righthind leg 3D, and left hind leg 3C to take the upright position. Thisends the motion.

Such a motion, with which the pet robot 1 can kick a ball, can produce afeeling that the pet robot 1 plays with a ball.

(3-4-2) Second ball response motion

Next, a second ball response motion will be described below.

When it finds a ball in the surroundings, the pet robot 1 walks close tothe ball until the ball is slightly off the front to the left (or theright) and then takes a basic upright position as shown in FIG. 65A.

Then the pet robot 1 bends the right and left forelegs 3B and 3A andright and left hind legs 3D and 3C as shown in FIGS. 65B and 65C to takea lower position and turns the head 4 toward the front to direct thehead 4 downward.

Next, the pet robot turns the head 4 to the right (or the left), whiledrawing the chin and then dynamically turns the head 4 off to the left(or right) forward, where the ball is, as shown in FIGS. 65F through67B. Finally, as shown in FIGS. 67C and 67D, while adjusting the head 4so that it faces the front, the pet robot 1 straightens the bent rightand left forelegs 3B and 3A and the bent right and left hind legs 3D and3C to return to the original upright position. This ends the motion.

Such a motion, with which the pet robot can head a ball, can produce afeeling that the pet robot 1 plays with a ball.

(3-4-3) Third ball response motion

Next, a second ball response motion will be described below. When thepet robot 1 finds a ball, it produces the third ball response motion.

When it finds a ball, the pet robot 1 walks close to a positionimmediately behind the ball and then takes a basic upright position asshown in FIG. 68A.

Next, the pet robot 1 draws back its entire body, while lowering itselfby bending the right and left hind legs 3D and 3C, as shown in FIG. 68B.In parallel, the pet robot 1 turns the head 4 from the rear to the frontto lower the head 4 sharply until the top of the head 4 faces forward.

In addition, while bending the knees, the pet robot 1 turns the rightand left forelegs 3B and 3A toward the rear to squeeze itself. Then asshown in FIGS. 69A through 69E, the pet robot 1 turns the head 4 towardthe rear to push the ball forward, while dynamically extending the bentright and left hind legs 3D and 3C to slightly move the entire bodyforward.

Finally, the pet robot 1 slightly straightens the right and leftforelegs 3B and 3A and the right and left hind legs 3D and 3C as shownin FIG. 69F to return to the original upright position. This ends themotion.

Such a motion, with which the pet robot 1 can head a ball, can produce afeeling that the pet robot 1 plays with a ball.

(3-4-4) Fourth ball response motion

Next, a fourth ball response motion will be described below.

When it finds a ball, the pet robot 1 walks close to the ball until theball is just in front of the robot and then takes a basic uprightposition as shown in FIG. 70A.

Next, the pet robot 1 moves the center of gravity so that its weightdoes not act on the left foreleg 3A and then positions the contactsurface of the left foreleg 3A a little above the ball by lifting theleft foreleg 3A so that the end of the leg draws an arc outward.

Then the pet robot 1 brings the contact surface of the left foreleg 3Ain contact with the ball from above by turning the shank in the leftforeleg 3A downward. Finally, the pet robot 1 performs the reverse ofthe actions in FIGS. 70A through 70F as shown in FIGS. 71B through 72Bto return to the original down position. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 plays with aball with interest, thus giving the user a lifelike impression.

(3-4-5) Other ball response motions

FIGS. 73A through 74E, 75A through 77F, 78A through 80D, and 81A through83B show other ball response motions, that is, fifth, sixth, seventh,and eighth ball response motions, respectively.

(3-5) Emotion expression motion

Next, motions with which the pet robot 1 expresses emotion will bedescribed below (these motions are hereinafter called emotion expressionmotions).

(3-5-1) First emotion expression motion

A first emotion expression motion will be described below. The pet robot1 produces the first emotion expression motion when it is down, with theright and left hind legs 3D and 3C straightened forward, and, forexample, a loud sound occurs in the neighborhood, or an object suddenlyappears before the robot.

That is, when the pet robot 1 is down as shown in FIG. 84A, and, forexample, a loud sound occurs in the neighborhood, or an object suddenlyappears before the robot, it lifts the right and left hind legs 3D and3C slightly for an instant. In parallel, the pet robot 1 turns the head4 back for an instant, bending the head 4, opens the mouth, and standsthe tail 5 for an instant. Then the pet robot 1 returns to the originaldown position as shown in FIG. 84C.

Such a motion can produce a feeling that the pet robot 1 is startled,thus expressing an emotion of surprise.

(3-5-2) Second emotion expression motion

Next, a second emotion expression motion will be described below.

The pet robot 1 produces the second emotion expression motion when itexpresses an emotion of anger.

When it is in a basic upright position as shown in FIG. 85A, the petrobot l moves the center of gravity so that its weight does not act onthe right foreleg 3B (or the left foreleg 3A), as shown in FIGS. 85B and85C and then swing the entire right foreleg 3B (or left foreleg 3A) backand forth of the pet robot, and in concert with this swings the shank3BY (3AY) in the right foreleg 3B (or the left foreleg 3A) back andforth as shown in FIG. 85D through 86F to act as if it scratches thefloor a few times. In parallel, the pet robot 1 directs the head 4downward, generating a feeling that it looks at the floor and flashes onand off a red LED, which has a shape appearing to express anger andfunctions as an eye.

After this action is completed, the pet robot 1 performs the reverse ofthe actions in FIGS. 85A through 85C as shown in FIGS. 87A through 87Dto return to the original upright position. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 scratches theground with anger, thus expressing an emotion of anger.

(3-5-3) Third emotion expression motion

Next, a third emotion expression motion will be described below. The petrobot 1 produces the third emotion expression motion when it feels adislike.

When the pet robot 1 is in a basic down position as shown in FIG. 88A,it lifts the right and left forelegs 3B and 3A as shown in FIGS. 88 Bthrough 88D so that the thighs 3BX and 3AX nearly level and turns thehead 4 to the right (or left) to direct it to the right (or left). Herethe pet robot 1 bends the knee 3BY to the extent that the contactsurface of the right foreleg 3B faces forward and bends the knee 3AY inthe left foreleg 3A more sharply than the knee 3BY.

Then the pet robot 1 turns the left foreleg 3A (or the right foreleg 3B)as it is from side to side a plurality of times as if to swing the leg,as shown in FIGS. 88E through 90A. After this action is completed, thepet robot 1 performs the reverse of the actions in FIGS. 88A through 88Das shown in FIGS. 90B through 90D to return to the original downposition. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 shows adislike, thus giving the user a lifelike impression.

(3-5-4) Other emotion expression motions

FIGS. 91A through 93A, 94A through 96A, 97A through 98E, 99A through99C, 100A through 102A, 103A through 105E, and 106A through 107D showthe flow of other emotion expression motions, that is, fourth, fifth,sixth, seventh, eighth, ninth, and tenth emotion expression motions,respectively.

(3-6) Idleness motions

Next, motions will be described below which the pet robot 1 produceswhen the condition recognizing mechanism 30 (FIG. 3) in the controller10 (FIG. 2) does not provide a specific recognition result (thesemotions are hereinafter called idleness motions).

(3-6-1) First idleness motion

A first idleness motion will be described below. The pet robot 1produces the first idleness motion when it is in a basic down positionas shown in FIG. 108A.

When the pet robot 1 is in the basic down position as shown in FIG.108A, it slowly lifts the right and left forelegs 3B and 3A, whileopening them apart outside, as shown in FIGS. 108B through 109C. Inparallel, the pet robot 1 bends the right foreleg 3B and shank 3AY inthe left foreleg 3A backward. Here the pet robot 1 is supported by therear end of the stomach of the body 2 and right and left hind legs 3Dand 3C.

After lifting the thighs 3BX and 3AX in the right and left forelegs 3Band 3A until they nearly level, as shown in FIG. 109C, the pet robot 1opens the mouth, while bending the head 4 backward, as shown in FIGS.109D through 111B. In parallel, while straightening the right and leftforelegs 3B and 3A and moving them back in such directions that the legsclose together, the pet robot 1 turns the legs down.

Then when the right and left forelegs 3B and 3A come in contact with thefloor as shown in FIG. 111C, the pet robot 1 directs the head 4 forwardto return to the original down position. This ends the motion.

Such a motion can produce a feeling that the pet robot 1 yawns,stretching itself, thus giving the user a lifelike impression.

(3-6-2) Second idleness motion

Next, a second idleness motion will be described below. The pet robot 1produces the second idleness motion when it slightly opens the right andleft hind legs 3D and 3C outward and straightens them forward as shownin FIG. 112A.

When the pet robot 1 is as shown in FIG. 112A, it turns the head 4 todraw a circle, as shown in FIGS. 112B through 113A. Here the mouth isopen.

Once the head 4 faces slightly up forward as shown in FIG. 113B, the petrobot 1 dynamically turns the head 4 obliquely down as shown in FIGS.113C through 113F. Here the speaker 20 (FIG. 2) outputs a sound ofsneezing.

When the head 4 faces downward, the pet robot 1 swings the head 4 fromside to side a few times. After completing the action, the pet robot 1directs the head 4 as before to return to the original down position.This ends the motion.

Such a motion can produce a feeling that the pet robot 1 sneezes, thusgiving the user a lifelike impression.

(3-6-3)

FIGS. 116A through 119E, 120A through 124A, 125A through 127A, 128Athrough 130B, 131A through 133A, and 134A through 136E show the flow ofother idleness motions, that is, third, fourth, fifth, sixth, seventh,and eighth idleness motions, respectively.

(3-7) Language motions

Next, language motions will be described below which the pet robot 1produces when it wants to inform the user of something (these motionsare hereinafter called language motions).

(3-7-1) First language motion

A first language motion will be described below. The pet robot 1produces the first language motion when it is in a basic down positionas shown in FIG. 137A.

When the pet robot 1 is in the basic down position in FIG. 137A, itlifts the right and left forelegs 3B and 3A almost to the level of theshoulders as shown in FIGS. 137B through 137E and then lowers the rightand left forelegs 3B and 3A so that their ends draw an arc, as shown inFIGS. 137F through 138E.

Then after slightly inclining the head 4 to the left (or right) as shownin FIGS. 138F through 140B, the pet robot 1 moves the right and leftforelegs 3B and 3A up and down a few times. After completing thisaction, the pet robot 1 brings the right and left forelegs 3B and 3A incontact with the floor to return to the original down position, as shownin FIG. 140C. This ends the motion.

With such a motion, the pet robot 1 can indicate a ball as shown inFIGS. 137B through 137E and express a want to convey a desire for a ballto the user.

(3-7-2) Other language motions

FIGS. 141A through 143A, 144A through 147E, 148A through 150F, 151Athrough 154A, 155A through 157A, and 158A through 161A show otherlanguage motions, that is, second, third, fourth, fifth, sixth, andseventh language motions, respectively.

(3-8) Other motions

FIGS. 162A through 165A, 166A through 168E, 169A through 171F, 172Athrough 174D, and 175A through 177D show the flow of motions which thepet robot 1 produces when it grows up (these motions are hereinaftercalled growth motions), that is, first, second, third, fourth, and fifthgrowth motions, respectively, as examples of other motions.

(4) Effect of the Embodiment

With motions, the pet robot 1 arranged as described above recovers froma tumble and presents a touch of a living thing or a robot.

Thus the pet robot 1 eliminates the need for the user to stand the robotwhen it tumbles. In addition, the robot gives the user affection for,and curiosity about, it with motions.

Because the pet robot 1 is adapted so that it recovers from a tumble andpresents a touch of a living thing or a robot with motions, thearrangement eliminates the need for the user to stand up the pet robot 1when it tumbles and allows the pet robot 1 to give the user affectionfor, and curiosity about, the robot with motions, thus enhancing theamusing characteristics of the pet robot 1.

(5) Other Embodiments

In the above-described embodiment, the present invention is applied tothe pet robot 1 arranged as shown in FIG. 1. However, the presentinvention is not limited to such an arrangement but can be applied to avariety of robots.

INDUSTRIAL APPLICABILITY

The present invention can be applied to pet robots.

What is claimed is:
 1. A four-legged robot whose body is connected atthe front right, front left, rear right, and rear left with legs,characterized in that said robot comprises: driving means for drivingthe legs separately from each other; and controlling means forcontrolling the driving means, and said controlling means controls thedriving means so that when the robot tumbles sideward, the driving meansturns the forelegs and hind legs under the body in such directions thatthe legs open apart from each other and then in such directions thatthey move away from the body.
 2. A four-legged robot whose body isconnected at the front right, front left, rear right, and rear left withlegs, characterized in that said robot comprises: driving means fordriving the legs separately from each other; and controlling means forcontrolling the driving means, and said controlling means controls thedriving means so that when the robot tumbles forward, the driving meansturns the legs at the front of the body until they are parallel in frontof the body and then turns the legs toward the rear of the body.
 3. Afour-legged root whose body is connected at the front right, front left,rear right, and rear left with legs, characterized in that said robotcomprises: driving means for driving the legs separately from eachother; and controlling means for controlling the driving means, and saidcontrolling means controls the driving means so that when the robottumbles backward, the driving means turns the legs at the rear of thebody in such directions that the legs move away from the body until theyare almost straight and then turns the legs toward the front of thebody.
 4. A four-legged robot whose body is connected at the front right,front left, rear right, and rear left with legs, characterized in thatsaid robot comprises: driving means for driving the legs separately fromeach other; and controlling means for controlling the driving means, andsaid controlling means controls the driving means so that the drivingmeans opens the legs radially and then bends the legs above the body. 5.A four-legged robot whose body is connected at the front right, frontleft, rear right, and rear left with legs and provided at the front witha head, characterized in that said robot comprises: driving means fordriving the legs and head separately from each other; and controllingmeans for controlling the driving means, and said controlling meanscontrols the driving means so that the end of one of said legs under thebody moves up and down at the back of the head.